1. Field of the Invention
The present invention relates in general to resonant compressors and more particularly to resonant compressors driven by electrodynamic linear motors. The invention has a wide range of applications, one example of which is use in refrigeration and air conditioning equipment and it will be described in detail in a configuration of that type.
2. Description of the Prior Art
Compressors employing electromagnetic drive means have long been known in the art; the use of electrodynamic drive means being a more recent development. Heretofore, resonant type compressors driven by electrodynamic linear motors have been limited by the requirements that they operate into a relatively constant load, and that the power source be stable, especially with respect to voltage and frequency. Perturbations in these parameters lead to overstroking. Much effort has been applied to this problem. Early attempts involved the use of complex control means which, while they could prevent overstroking, did not solve the underlying problem. The more recent use of springs of various types which increased in stiffness towards the end of a stroke were brute force cures of the symptoms along the same line.
I have discovered that the uncompensated combination of an electrodynamic linear motor with a resonant compressor is only conditionally stable, that is, that instabilities in supply voltage or in load will cause overstroking.
Accordingly, it is an object of this invention to provide a new and improved electrodynamic linear motor, resonant type compressor which overcomes one or more of the limitations of prior art type compressors and which is inexpensive and simple to manufacture.
It is another object of this invention to provide a new and improved electrodynamic linear motor, resonant type compressor system having a higher power factor than was heretofore possible without the use of power factor correction capacitors.
It is another object of this invention to provide a new and improved electrodynamic linear motor, resonant type compressor having a higher output under a wide range of load conditions than was heretofore possible.
It is still another object of this invention to provide a new and improved electrodynamic linear motor, resonant type compressor having an inherent stability and being relatively insensitive to variations in line voltage and in load.
It is another object of this invention to provide a new and improved electrodynamic linear motor, resonant type compressor having compensating means to oppose overstroking and prevent piston strike.